feat: Refactor user and thought models to use UUIDs instead of integers

- Updated user and thought models to utilize UUIDs for primary keys.
- Modified persistence functions to accommodate UUIDs for user and thought IDs.
- Implemented tag functionality with new Tag and ThoughtTag models.
- Added migration scripts to create new tables for tags and thought-tag relationships.
- Enhanced thought creation to parse hashtags and link them to thoughts.
- Updated tests to reflect changes in user and thought ID types.

thoughts-backend/migration/src/lib.rs

@@ -3,6 +3,7 @@ pub use sea_orm_migration::prelude::*;
 mod m20240101_000001_init;
 mod m20250905_000001_init;
 mod m20250906_100000_add_profile_fields;
+mod m20250906_130237_add_tags;
 
 pub struct Migrator;
 
@@ -13,6 +14,7 @@ impl MigratorTrait for Migrator {
             Box::new(m20240101_000001_init::Migration),
             Box::new(m20250905_000001_init::Migration),
             Box::new(m20250906_100000_add_profile_fields::Migration),
+            Box::new(m20250906_130237_add_tags::Migration),
         ]
     }
 }